Observation of an enhancement in e+e- → γ(1S)π+π-, γ(2S)π+π-, and γ(3S)π+π- production near √s=1.89 GeV

We measure the production cross sections for e(+)e(-) -> gamma(1S)pi(+)pi(-), gamma(2S)pi(+)pi(-), and gamma(3S)pi(+)pi(-) as a function of root 5 between 10.83 GeVand 11.02 GeV. The data consist of 8.1 fb(-1) collected with the Belle detector at the KEKB e(+)e(-) collider. We observe enhanced production in all three final states that does not agree well with the conventional gamma(10860) line shape. A fit using a Breit-Wigner resonance shape yields a peak mass of [10 888.4(-2.6)(+2.7)(stat) +/- 1.2(syst)] MeV/c(2) and a width of [30.7(-7.0)(+8.3)(stat) +/- 3.1(syst) MeV/c(2).